Comparing the lower limb tasks questionnaire to the Western Ontario and McMaster Universities Osteoarthritis Index: agreement, responsiveness, and convergence with physical performance for knee osteoarthritis patients.

Abstract

To compare the Lower Limb Tasks Questionnaire (LLTQ) with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) in terms of agreement, responsiveness, and convergence. Cross-sectional with an exploratory repeated-measures subsample analysis. Community-based seniors' centers and arthritis clinics. Individuals with symptomatic knee osteoarthritis (N=76) participated, with a subsample of 18 participants contributing to the pre- and postarthroplasty subanalysis. Not applicable. Bland and Altman plots of agreement with 95% limits of agreement, statistical responsiveness, and standardized response mean (SRM) were calculated for LLTQ and WOMAC subscales. Both t tests and Wilcoxon rank-sum tests were used to examine changes in pre- and postarthroplasty self-reported function, 50-ft walk speed, stair ascent/descent speed, and isometric quadriceps strength. The agreement (bias) of the LLTQ activities of daily living (ADL) subscale when compared with the WOMAC physical function (PF) subscale was 1%±10% (mean ± SD), and the 95% limits of agreement were -19% to +22%. The statistical responsiveness of the WOMAC-PF and LLTQ ADL was 1.17 and -.63, respectively. The SRMs for these scales were .90 and -.61, respectively. The WOMAC-PF scores showed a notable improvement over the first 6 weeks postarthroplasty, while LLTQ ADL scores were unchanged. The objective measures of function were all significantly worse at 6 weeks. The LLTQ demonstrated adequate agreement with the WOMAC and acceptable responsiveness for use in place of the WOMAC in nonspecialized clinics. The LLTQ may more accurately represent functional status after total knee arthroplasty, but further study in larger samples is recommended.